03.09.09(a): Introduction

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School's M1 CNS sequence

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  • 1. Author(s): Peter Hitchcock, PH.D., 2009License: Unless otherwise noted, this material is made available under the terms ofthe Creative Commons Attribution–Non-commercial–Share Alike 3.0 License:http://creativecommons.org/licenses/by-nc-sa/3.0/We have reviewed this material in accordance with U.S. Copyright Law and have tried to maximize your ability to use, share, andadapt it. The citation key on the following slide provides information about how you may share and adapt this material.Copyright holders of content included in this material should contact open.michigan@umich.edu with any questions, corrections, orclarification regarding the use of content.For more information about how to cite these materials visit http://open.umich.edu/education/about/terms-of-use.Any medical information in this material is intended to inform and educate and is not a tool for self-diagnosis or a replacement formedical evaluation, advice, diagnosis or treatment by a healthcare professional. Please speak to your physician if you have questionsabout your medical condition.Viewer discretion is advised: Some medical content is graphic and may not be suitable for all viewers.
  • 2. Citation Key for more information see: http://open.umich.edu/wiki/CitationPolicyUse + Share + Adapt { Content the copyright holder, author, or law permits you to use, share and adapt. } Public Domain – Government: Works that are produced by the U.S. Government. (USC 17 § 105) Public Domain – Expired: Works that are no longer protected due to an expired copyright term. Public Domain – Self Dedicated: Works that a copyright holder has dedicated to the public domain. Creative Commons – Zero Waiver Creative Commons – Attribution License Creative Commons – Attribution Share Alike License Creative Commons – Attribution Noncommercial License Creative Commons – Attribution Noncommercial Share Alike License GNU – Free Documentation LicenseMake Your Own Assessment { Content Open.Michigan believes can be used, shared, and adapted because it is ineligible for copyright. } Public Domain – Ineligible: Works that are ineligible for copyright protection in the U.S. (USC 17 § 102(b)) *laws in your jurisdiction may differ { Content Open.Michigan has used under a Fair Use determination. } Fair Use: Use of works that is determined to be Fair consistent with the U.S. Copyright Act. (USC 17 § 107) *laws in your jurisdiction may differ Our determination DOES NOT mean that all uses of this 3rd-party content are Fair Uses and we DO NOT guarantee that your use of the content is Fair. To use this content you should do your own independent analysis to determine whether or not your use will be Fair.
  • 3. Introductory Lecture M1 – CNS Sequence Peter Hitchcock, Ph.D.Winter, 2009
  • 4. Introduction to today s lecture:I.  Introduction to the faculty and the Normal CNS, Special Senses, Head & Neck SequenceII.  Anatomical planes and major axes of the central nervous systemIII.  Principal cell types in the CNSIV.  Specialized stains and what they revealV.  Schematic representation of the functional organization of the CNSVI.  Regional anatomy of the central nervous systemVII.  Functional subdivisions, pathways and relevant conceptsVIII.  Topographic organizationIX.  Blood supply to the CNSX.  The cerebrospinal fluid
  • 5. Why is learning neuroanatomy such a challenge?You will simultaneously learn:1) regional anatomy (spinal cord,brainstem, etc.)2. surface (gross) anatomy3. internal anatomy4. names and locations of nucleiand tracts and the pathways theyform5. functions of the variouspathways in the CNS6. blood supplyS neuronal cell biology nerve development and regeneration neurotransmitters chemical neuroanatomyGross AnatomyHistologyPharmacokinetics Source Undetermined Source Undetermined
  • 6. There are three principal planes of sectionthat are used for viewing the brain:horizontal, frontal (or coronal) andsagittal. U.S. Federal Government Source Undeterminedfrontal section through the cerebral hemispheres
  • 7. •  There are three principal axes along which the internal anatomy of the nervous system is organized: –  rostral-caudal axis –  dorsal ventral axis –  medial-lateral axis•  During its embryonic development the human brain bends (known as a flexure). As a result, the dorsal-ventral plane changes as one moves along the neuraxis, from rostral telencephalon to the caudal spinal cord.•  Several terms are used to indicate the relative positions of structures or tracts in the brain: –  Dorsal - above or superior –  Ventral -below or inferior –  Rostral -toward the front –  Caudal - toward the back –  Medial - toward the midline Source Undetermined –  Lateral - away from the midline –  Ipsilateral - on the same side –  Contralateral - on the opposite side
  • 8. •  There are two fundamental cell types in the CNS: neurons (10X109) and glia (10-50X more numerous than neurons).•  Neurons communicate to each other via specialized junctions known as synapses.•  Neurons are polarized cells that are specialized to receive synapses on dendrites and relay electrical impulses to other neurons via their axons (also called Images of glia fibers) and their synapses. and neurons•  A collection of neuronal cell bodies outside the CNS is called a ganglion. removed•  A collection of neuronal cell bodies within the CNS is called a nucleus.•  A discrete bundle of axons outside the CNS is known as a nerve.•  A discrete bundle of axons within the CNS is known as a tract (lemniscus, fasciculus). (read the handout for more details on tracts)•  Nuclei and tracts that are linked by synapses serve a common function are generally referred to as a pathway.
  • 9. Axons that form a tract: have cell bodies in a common nucleus synapse onto a common target (or set of targets) perform a common function, e.g., somatic sensation, voluntary movementTracts are often named based on the site of origin and termination of their axons: spinothalamic tract – from the spinal cord to the thalamus corticospinal tract – from the cerebral cortex to the spinal cordThe names of tracts often identify their relative location within the CNS white matter: lateral spinothalamic tract – lateral in the spinal cord medial lemniscus – near the midlineTracts can carry information either up or down the neuraxis ascending tract (spinothalamic tract) - sensory function descending tract (corticospinal tract) - motor functionTracts that carry sensory or motor information are generally organized in parallel: pain and temperature vs. fine discrimination
  • 10. The locations and spatial relationships of nuclei and tracts define theinternal anatomy of the CNS. The functions subserved by the variousnuclei and tracts define the functional anatomy of the CNS.
  • 11. Regions of the brain that contain cell bodies are given the general descriptive term,gray matter. Source Undetermined Source Undetermined Spinal cord cerebral hemisphereswhite matter gray matter gray matter white matter Regions of the brain that contain axons are given the general descriptive term, white matter.
  • 12. Golgi-stained neurons (cortex) Visualizing neurons and axons in the central nervous system nucleic acid stain (lateral geniculate nucleus [dorsal thalamus]) Source Undetermined myelin-stain (brainstem) Source Undetermined Source Undetermined
  • 13. A schematic representation of the nervous system organization and function•  The nervous system of all animals performs 3 fundamental biological functions: –  Monitor and regulate the internal environment –  Monitor the external environment –  Initiate behaviors based on infor-mation from both the internal and external environments•  You are generally unaware of the majority of the functions performed by your nervous system. glands sensory systems: transduction, transmission, perception motor systems: mentation, transmission, behavior P. Hitchcock
  • 14. Forebrai nREGIONAL ANATOMY OF THE CNS•  The CNS can be divided into 6 parts: 1) spinal cord 2) medulla (meyelencephalon) 3) pons (metencephalon) Diencephalon 4) midbrain (mesencephalon) 5) thalamus (diencephalon) Midbrain 6) cerebral hemispheres Pons Hindbrain (telencephalon) Brainstem•  These terms may be used Cerebellum interchangeably. Medulla Spinal cord: cervical thoracic lumbar sacral Patrick J. Lynch, wikimedia commons
  • 15. These two diagrams model representative pathwaysof the somaticsensory and motor systems,respectively. J.H. Martin. Neuroanatomy: Text and Atlas.McGraw-Hill, 2003. 3rd Edition. afferent axons - carry information into the CNS efferent axons - carry information out of a structure decussation - site where axons cross the midline
  • 16. Sensory information from theperiphery enters the brain in a verysystematic manner. This creates a Sensory dermatomesspatial order, which is preservedthroughout the sensory pathways. Haines. Fundamental Neuroscience. Churchill Livingstone, 2002. 2nd ed. Source Undetermined
  • 17. PrimaryALL Sensory and Motor sensory cortexpathways aretopographically organized. Sensory: There is a point-to point relationship between a peripheral sensory Modified from Tristram, wikispaces structure and its pathway in the CNS. Primary motor cortex Motor: Pathways in the CNS are organized according to somatic muscle groups in the periphery.homunculus=little man Modified from Tristram, wikispaces
  • 18. Sensory frominformation from theneck and below entersthe CNS via spinalnerves, whose axonsascend in white mattertracts.Depending on thenature of the sensation,axons may or may notsynapse in the spinalcord. J.H. Martin. Neuroanatomy: Text and Atlas.McGraw-Hill, 2003. 3rd Edition.
  • 19. Sensory axons may (or maynot) synapse on nuclei in thebrainstem. If they do, thename of the tract changes.All axons carrying sensoryinformation synapse indiscrete nuclei within thedorsal thalamus. Gray s Anatomy
  • 20. Cerebral cortex is highly specialized.Somatic sensory information carried by axons from the dorsalthalamus synapse on neurons in the postcentral gyrus (primarysomatic sensory cortex) in the parietal lobe. Expressive Receptive Source Undetermined
  • 21. The brainstem controlsnumerous bodily functions.Injuries to the brainstem canbe life threatening.The brainstem also receivessensory information from thehead and contains the motorneurons that innervatemuscles of the neck, headand face. U.S. Federal Government
  • 22. The internal anatomy of thebrainstem is complex. J.H. Martin. Neuroanatomy: Text and Atlas. McGraw-Hill, 2003. 3rd Edition. Gray s Anatomy
  • 23. Syringomyelia Brown-Séquard syndrome J.H. Martin. Neuroanatomy: Text and Atlas. McGraw-Hill, 2003. 3rd Edition.Injures to the brainstem and spinal cord giverise to specific sensory and motor deficits. J.H. Martin. Neuroanatomy: Text and Atlas. McGraw-Hill,Injuries to the spinal cord produce sensory 2003. 3rd Edition.deficits that respect myotomal boundaries.Place a lesion = what are the symptoms?Describe the symptoms = can you place thelesion?
  • 24. Axons that carry motor commands for voluntary movementsoriginate in the precentral gyrus (primary motor cortex) of thefrontal lobe, descend into the brainstem and spinal cord andsynapse on motor neurons that innervate skeletal muscles. Expressive Receptive Source Undetermined
  • 25. An example of a motorpathway.The corticospinal tract extendsfrom the precentral gyrus tothe spinal cord and subservesthe voluntary control ofskeletal muscles.Although clinically important,the corticospinal system isnumerically a minorcomponent in the control ofskeletal muscles. Haines. Fundamental Neuroscience. Churchill Livingstone, 2002. 2nd ed.
  • 26. The cerebellum is a component of the motor system thatis not involved in unconscious control of skeletalmuscle. Source UndeterminedDiseases of the cerebellum are known as ataxias.
  • 27. Special senses:VisionHearingBalance The Regents of the University of Michigan
  • 28. The CNS is highly vascularized and interruption in the bloodsupply is a common form of nervous system injury Source Undetermined
  • 29. The CNS is filled with and surroundedbycerebrospinal fluid (csf).Internally: -lateral ventricles -3rd ventricle -4th ventricleExternally: -subarachnoid spaceCSF is a secretory product thatcirculates through the ventricles andreturns to the venous side of the brainvasculature Source Undetermined
  • 30. Additional Source Information for more information see: http://open.umich.edu/wiki/CitationPolicySlide 5: Sources UndeterminedSlide 6: Source Undetermined; U.S. Federal Government, http://en.wikipedia.org/wiki/File:BodyPlanes.jpgSlide 7: Source UndeterminedSlide 11: Sources UndeterminedSlide 12: Sources UndeterminedSlide 13: Peter HitchcockSlide 14: Patrick J. Lynch, Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Brain_human_sagittal_section.svg, CC:BY http://creativecommons.org/licenses/by/2.5/Slide 15: Source: J.H. Martin. Neuroanatomy: Text and Atlas.McGraw-Hill, 2003. 3rd Edition.Slide 16: Source Undetermined; Haines. Fundamental Neuroscience. Churchill Livingstone, 2002. 2nd ed.Slide 17: Original sources, tristram, Wikispaces, http://tristram.wikispaces.com/file/view/homunculus.gif, CC:BY:SA http://creativecommons.org/licenses/by/3.0/Slide 18: J.H. Martin. Neuroanatomy: Text and Atlas.McGraw-Hill, 2003. 3rd Edition.Slide 19: Gray s Anatomy, http://www.bartleby.com/107/Slide 20: Source UndeterminedSlide 21: U.S. Federal GovernmentSlide 22: J.H. Martin. Neuroanatomy: Text and Atlas. McGraw-Hill, 2003. 3rd Edition.; Gray s AnatomySlide 23: J.H. Martin. Neuroanatomy: Text and Atlas. McGraw-Hill, 2003. 3rd Edition.; J.H. Martin. Neuroanatomy: Text and Atlas. McGraw-Hill, 2003. 3rd Edition.Slide 24: Source UndeterminedSlide 25: Haines. Fundamental Neuroscience. Churchill Livingstone, 2002. 2nd ed.Slide 26: Source UndeterminedSlide 27: The Regents of the University of MichiganSlide 28: Source UndeterminedSlide 29: Source Undetermined